import math

point =list(map(float, input().split()))
p1 = point[0]
p2 = point[1]
p3 = point[2]
p4 = point[3]

l = math.sqrt((p3 - p1)**2 + (p4 - p2)**2)

print(l) import math math point =list(map(float, input().split())) point list(map(float, input().split())) list map(float, input().split()) map float input().split() ().split () input split p1 = point[0] p1 point[0] point 0 p2 = point[1] p2 point[1] point 1 p3 = point[2] p3 point[2] point 2 p4 = point[3] p4 point[3] point 3 l = math.sqrt((p3 - p1)**2 + (p4 - p2)**2) l math.sqrt((p3 - p1)**2 + (p4 - p2)**2) math.sqrt math sqrt (p3 - p1)**2 + (p4 - p2)**2 (p3 - p1)**2 p3 - p1 p3 p1 2 (p4 - p2)**2 p4 - p2 p4 p2 2 print(l) print l p4 = point[3] point[3] p4 p2 = point[1] point[1] p2 point =list(map(float, input().split())) list(map(float, input().split())) point p3 = point[2] point[2] p3 p1 = point[0] point[0] p1 l = math.sqrt((p3 - p1)**2 + (p4 - p2)**2) math.sqrt((p3 - p1)**2 + (p4 - p2)**2) l
import math

point =list(map(float, input().split()))
p1 = point[0]
p2 = point[1]
p3 = point[2]
p4 = point[3]

l = math.sqrt((p3 - p1)**2 + (p4 - p2)**2)

print(l)